Arthroplasty in Cats

Arthroplasty is a procedure which involves excising or replacing a joint. Arthroplasty is typically recommended for cases in which preserving the joint is not possible. Most cats that require arthroplasty are younger than two years old, although joint conditions can affect cats of any age Arthroplasty is most commonly performed on the hip or pelvis, and may also be known as femoral head and neck ostectomy (FHO). The femoral head is a type of ball joint which attaches the back leg to the pelvis. Animals have two femoral heads, one on either side of the pelvis. One or both femoral heads may need to be removed depending on the severity of the condition. Total hip joint replacement is not usually considered for smaller animals, since FHO is a less invasive procedure that costs less, heals quicker, and is more effective overall.

The exact procedure may vary depending on the underlying condition as well as the area affected. The general procedure steps for FHO are outlined below.

1. The cat must be fasted prior to surgery according to veterinary instructions.
2. The cat will then be anesthetized. A catheter and breathing tube will be placed before the operative area is clipped, cleaned, and prepped. 
3. Analgesics will be administered throughout surgery.
4. The surgeon will make the initial incision over the hip.
5. Once the hip is exposed, the affected femoral head and neck will be excised.
6. The surgery site will then be sutured.
7. Postoperative x-rays will be taken to ensure the entire femoral head has been removed.
8. The femoral head and neck may be submitted for histopathologic evaluation.
9. Following FHO, fibrous tissue will develop in the femoral head’s absence, preventing the bones from rubbing together. The muscles, rather than the ball joint, will support the hip once the femoral head(s) has been removed.

The efficacy of surgery will depend on the underlying condition as well as the joint(s) affected. In most cases, arthroplasty is effective. Cats will be able to put a little bit of their weight on the affected hind limb approximately two weeks following surgery. Most cats make a full recovery within two to three months.

Following surgery, cats will be prescribed analgesics and anti-inflammatories to manage pain and prevent inflammation. Antibiotics may also be prescribed in some cases. Cats may be required to wear an Elizabethan collar until the sutures are removed or absorbed to prevent irritation of the surgery site. Unlike most joint surgeries, the cat will not be required to rest following surgery. Exercise is encouraged to ensure the hip retains function and motion. The surgeon will recommend rehabilitation therapy according to the cat’s specific needs to restore normal function to the hip. This typically involves swimming once the incision site has healed. Follow-up appointments will be scheduled two weeks following surgery to remove sutures, and again two months later to monitor healing progress.

The cost of arthroplasty in cats will vary based on standards of living and additional costs incurred, including medications, laboratory costs, supportive care, and rehabilitation therapy. On average, arthroplasty, particularly FHO, costs $1,000. 

Arthroplasty is not recommended for animals whose bones have not fully developed. Development is typically complete by approximately nine to ten months of age. FHO will result in a slight shortening of the limb. However, this does not affect most animals and does not normally detract from limb function. There is a slight chance that poor range of motion can occur in the hip following surgery, although this is normally attributed to a lack of proper rehabilitation. A rare complication of FHO is sciatic nerve damage. Infection rarely happens in joint surgeries, but is possible.

In some cases, conditions requiring arthroplasty cannot be prevented because of genetics or age. However, owners can prevent traumatic injury and fracture by ensuring their cats do not engage in activities which may result in traumatic injury, including jumping from heights or becoming involved in an automobile accident.